Watch List: Caroline Wozniacki headlines Istanbul Cup return

Caroline Wozniacki, the top seed at the Istanbul Cup, is looking to improve upon a fourth round appearance at Wimbledon.

The Watch List returns to spotlight the must-know storylines for the upcoming week in tennis. The WTA welcomes the return of the Istanbul Cup with Caroline Wozniacki in the field and points are up for grabs in Europe and South America on red clay and hard courts.

Hamburg Open

Every year, we roll our eyes at Hamburg's bet-at-home Open, a tournament with an online betting company as its title sponsor. (Side note: Is capitalizing your company name not cool anymore?) The ATP 500 event got a big boost last year when Roger Federer decided to take a wildcard, but this year the field is more of what you would expect from a post-Wimbledon clay tournament. No. 7 David Ferrer is the top seed with defending champion Fabio Fognini, Tommy Robredo and Alexandr Dolgopolov rounding out the top four seeds. Also in the field are young guns Dominic Thiem, Jerzy Janowicz and last week's champion in Stuttgart, Roberto Bautista Agut.

Claro Open Colombia

Colombia is a long way to go for an ATP 250, but with the smaller and easier field, it may just be worth it. No. 14 Richard Gasquet and defending champion Ivo Karlovic headline the 28-player field. Karlovic is coming off a run to the Newport final where he lost to Lleyton Hewitt in three sets on Sunday. The most surprising name in the field in Bernard Tomic, now ranked No. 122, who took a wildcard into the tournament. Not sure we'll see Tomic doing this every year, but it must mean (hopefully) that he has enough faith in his body that he's willing to fly anywhere just to get matches.

Istanbul Cup

The Istanbul Cup, a WTA International-level hard court event that was shelved when Istanbul won the right to host the WTA Championships in 2011, returns this year. No. 15-ranked Caroline Wozniacki is the top seed and will try to get back to her winning ways. She played some good tennis at Wimbledon and reached the fourth round, but she'll be tested early here with a first-round match against Belinda Bencic. Roberta Vinci, a finalist last week in Bucharest, Klara Koukalova and Elina Svitolina are the other three top seeds.

Swedish Open

There's no Serena Williams in Bastad this year. The No. 1 has not recovered from whatever ailed her at Wimbledon and withdrew last week. In a twist of irony, she's been replaced by her Wimbledon vanquisher Alize Cornet, ranked No. 21. Cornet took a last minute wildcard and will be the top seed of what is a very weak field, with just two top 40 players in the tournament. Anastasia Pavlyuchenkova is the No. 2 seed.